Burner help

Not sure if this is the correct solution section or not, but last fall when I started the business up, I purchased a Karcher Hds3205be hot water Skid from a local guy that was retiring. It’s a decent sized Skid with a 16hp vanguard and a 3500psi 5.6gpm pump. Everything worked great for the last 4-5 months. Now the burner won’t kick on when I try to use it. It just flashes a light on the control panel.the light says RM 110 next to it. The only thing I can find online says something about scale protection. Can anyone give me insight on this? download

I don’t know a whole lot about hot water units except last year I completely tore down a Karcher hds 1200 be to every last nut and bolt to restore it. It also has a 16 hp Vanguard. The burner didn’t work when I got it so I had to do a lot of digging and talking to people. My Karcher is quite a bit older than yours and doesn’t have a digital panel for troubleshooting though. If I had to guess I would say you have a buildup of scale in the system. I don’t know if you’ve ever seen the scale in the bottom of an old hot water heater but it’s amazing how much builds up over the years. I’m sure a lot of it’s dirt and sand too.

I would first start out but giving the system a good flush and clean the thermostat probe. I’m not sure what other sensors or probes yours might have but I would check anything that touches water. They have a chemical scale remover that you run through to clean it.

By the way what pump is on your machine?

1 Like

If there is a local PW dealer, your best bet is to take it there to get serviced. Your coil may need cleaning plus other maintenance.

3 Likes

Check your flow switch. Mine gets corrosion on it from time to time and will hang up. Itll keep the burner from firing off or itll get hung up and keep the burner going at which point you ll get to see some really hot water and really expensive equipment go up in flames. Ha…

Or take it to a dealer and let them look at it which is probably best.

1 Like

@CCS I have a question that has to do with scale if you don’t mind answering. The old Karcher I have is fed water from the water supply to a box and from there it feeds the pump. The box has a float that shuts off the water supply so water doesn’t overflow out of the box if you aren’t running the pressure washer. On top of the box is a compartment with solenoid which is suppose to be for water softening detergent or whatever you call it. The manual talks about always testing for water hardness and adjusting the softener feed as needed. I don’t see people doing this but I could be wrong. Do they still recommend adding water softener to the water? It seems like most of the pictures I’ve seen of setups the supply is plumbed right to the pump so not sure where it would be added. I have never messed with water softener the few times I’ve used it but just wondering if anyone does? I guess most water today is soft water unless outside city limits so I’m guessing it’s no longer a concern?

1 Like

Thanks man. I’d really like to tear into it and clean the burner out, but I have no clue what I’m getting myself into as I can’t find any info about them.

The are videos on youtube about descaling. I’d start with that since that’s the error you’re getting. Or just call a Karcher dealer.

4 Likes

You don’t have to tear the burner itself apart for descaling. CCS mentioned his flow switch has caused the same problem. The flow switch isn’t hard to pull off at all. Not much harder than a spark plug. If you have any inline filters check those also.

As Racer recommended watching a video on descaling is a good idea.

2 Likes

@marinegrunt my skid had the same style box with float, i call it a buffer box( as it is supposed to act as a miniature buffer for water ). I disconnected the box years ago and never use it. As far as the water softening detergent box within the buffer box, ive never seen one before nor heard of such. I understand the concept but unless you run some really hard water over years and years i wouldnt worry about it. I know dealers sell descaler and such but ive got a machine with about 2500 hours on it that has never seen an ounce of descaler an it seems to work just fine. (But then again that could also be why i have to replace flow switches every other year due to my own ignorance haha)

As far as flow switches go theyre a very simple concept, they work off a flow actuated switch which consist of a magnet and some electrical contacts inside. Ive had to take mine apart and just clean a little bit of rust or debris off from time to time, then they will work fine again. Usually a good way to test is by simply using a ohm meter. Im not electrical expert but years of dealing with the stuff and you get to know what tends to go wrong for the most part.

Theres some good videos on youtube and wiring diagrams on google that might help explain further how the burners are set up to operate.

1 Like

Thanks for the explanation on everything. The water softener tank on mine has a crack and was epoxied by someone. I had looked into ordering a new tank but could only find one for sale in the UK and it was like $200 plus shipping. I’m glad to hear I don’t need it. I’ll probably get rid of the mini buffer tank the same way you did.

I remember messing with the flow switch when I was troubleshooting the heater side of my pressure washer. In order to troubleshoot without the machine running I activated the flow switch with a strong magnet. I remember finding a really good troubleshooting guide to help with pressure washer heating systems. It was extremely helpful in troubleshooting and crossing things off the list. I’ll have to see if I can post it for 1badeagle. It definitely helped me understand a little how the system works.

Thanks again

1 Like

My Skid has that small(about 1 gallon) tank on it too. I run two buffer tanks so nothing runs through that little tank. Im pretty tired so I might need to re-read this in the morning, but are you saying I can remove that tank?

Yea you can remove it or unhook the hose from it. I just run a hose from my 335 gal buffer tank straight to the pump. Which is what most people would recommend if youve got a belt driven trailer mounted unit.

1 Like

I’m going to have to take a look at it tomorrow. My Skid has the hose hookup on the front and a ball valve that you can direct it through the little tank or straight to the pump.

The little water tank on mine is identical to yours. The white plastic tank on top is the same too. It looks like yours was completely taken out of use. If you didn’t have the ball valve there the hose running from the bottom of the blank tank would run to your pump. You then hook the supply line into the filter that’s located on the frame above the ball valve. If you want to save on room I’d get rid of it. You could then get rid of the ball valve. I found a manual on mine and it says the white tank on top is for water softener detergent. I’m glad to hear nobody uses it.

To clean the flow switch there should be a screw or bolt on the end. If you look on the left side of the picture you can see a bolt head right below where the wire enters the switch. Just take that out and you’ll have access to the magnet.

flow switch

It should be a brass covered magnet… Mine looked something like this.

Flow switch magnet

Just pull the magnet out and get the scale off of it. I know I mentioned it already but make sure the water filter isn’t dirty. A dirty filter can slow down flow too.

Here’s a diagram of how my flow switch is set up. With it also being a Karcher I would think they would be somewhat similar. In the diagram below 7 is the flow switch body. 3 is the screw/bolt or plug on the end, 4 is an o-ring, 5 is a spring, and 6 is the piston/magnet. Number 6 is what you’re after. Be sure to clean the spring too. #1 is the reed. It’s attached to the wires. It’s only held in by one screw and just slides out. It doesn’t make contact with water so it shouldn’t need to be removed or cleaned.

Thank you for the reply. I just want to clarify that the picture I posted of my burner is the switch part you are talking about?

I’m not 100% sure if the picture you posted is your flow switch or not but looks like it might be. If you posted a picture of the end where the wire attaches I could probably tell you because you would be able to see the screw or plug below the wire. Just try and compare the pictures above to yours. The shape of the body might be a little different but the rest should be similar. When you do start unscrewing the screw/plug be careful so you don’t lose the spring.

1 Like

Alright thanks man. I’m at my day job now, so I’ll have to look when I get up in the morning